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Janus Nanoparticles as Novel Ferroelectric Materials (Janus Ferroelectrics)
Date du début: 1 juin 2012, Date de fin: 31 mai 2014 PROJET  TERMINÉ 

The goal of this proposal is the generation of new ferroelectric materials based on bifunctional monolayer-protected metal nanoparticles (MPMNs) and supracrystals based on these anisotropic MPMNs. These Janus nanoparticles, named such for their characteristic pair of hemispherical faces, are expected to exhibit novel ferroelectric properties due to their inherent non-centrosymmetry and resulting permanent dipole. In addition, these MPMNs are expected to exhibit superparaelectric properties. This research will create the first such materials using several combinations of ligands in the protecting monolayer, such as alkanethiols and fluorinated alkanethiols. The work will begin with a systematic study, allowing optimization of synthetic parameters for forming Janus MPMNs. The ferroelectric properties of these Janus nanoparticles will be unlike any observed for MPMNs previously, due to their ubiquitous centrosymmetry and corresponding lack of a permanent dipole. Furthermore, the properties observed will be novel with respect to existing ferroelectrics due to its composition of nonferroelectric metals and organic ligands. Components with inherent ferroelectric properties, such as BaTiO3 and vinylidene fluoride, will then be integrated into the anisotropic materials. The integration of natively ferroelectric components into a system with emergent ferroelectric properties is expected to produce entirely novel multiferroic materials. The assembly of Janus MPMNs into supracrystals will also be explored in detail. The assembled supracrystals are expected to exhibit non-centrosymmetry, yielding a second class of novel ferroelectric and piezoelectric materials Ferroelectric materials can also be integrated into these supracrystals, yielding products with more complex and tunable properties.

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